The transmission on my 98A4 Avant wagon is slipping. Its an automatic and there is problems shifting after the car gets hot. After driving for 2 hours the temperature gage goes to 1/2 and the outside temp reading goes to 98 degrees. Does anyone know if this is the tranny or just the computer related stuff.

If it is the trans, is there a place you recommend to buy a certified used transmission with computer

Thanks